This invention relates generally to methods and apparatus to be used in food processing plants for filling containers with food materials.
The canning of certain food materials, such as spinach, involves a number of difficult and unusual requirements. The customary procedure is to introduce the spinach into cans immediately after blanching and before sealing and heat processing. This requires close weight control of each container. Generally the lower fill weight limit must be such as to meet minimum weights to comply with the governmental standards. The upper weight limit is important for economic reasons, and also because a weight less than an upper limit is of importance in assuring product sterility and safety after heat processing. After spinach has been blanched, it is difficult to handle and does not have uniform volume to weight ratios. The material is wet and limp as a result of blanching. Thus it does not lend itself to handling by mechanical filling machines where it is necessary for the material to have a relatively fixed volume-to-weight ratio.
Because of the foregoing, spinach is universally introduced into cans by manual labor. In such manual operations it is necessary to perform the collective functions of sorting the material for quality, manually introducing the material into the cans, and then checking the weight of each container. If the can is underweight then additional material must be added, or if it is overweight some must be removed. The labor productivity in such operations is relatively low, seldom exceeding five one-pound cans per minute per laborer.
Insofar as applicant is aware, no method or apparatus has been available to the canning industry for filling cans with measured amounts of spinach or like leafy vegetable, and which is capable of carrying out such operations in an efficient and automated manner, without manual labor.
Many other materials likewise present similar can-filling problems, including such leafy vegetables as cabbage, kale and collard greens which become limp when blanched. Also certain vegetables that are stringy and tend to be fluffy, when fresh or after blanching, such as green beans sliced lengthwise, sauerkraut (sliced cabbage), and shoestring carrots and beets, present some of the same problems.
In some instances, the maintenance of fixed volume-to-weight ratios is important although the material may not be leafy or stringy. An example is the canning of peaches or like fruit which is introduced into cans in particulate form with insufficient syrup to fill the voids.